Hey guys, I have had an issue with my blazer for a while now. Some days my blazer will start up by barley turning the key, other days I have to hold it down almost as if its not going to start at all. Some times I have to give it multiple shots before it will fire up. Also, when moving from a stopped position, when it gets to the 1st, 2nd and sometimes 3rd gear it seems like the blazer surges, kind of like if you were to let up on the gas then floor it for a second. It also gets real bad at highway speeds. RPMs tend to fluctuate between 1800-2000 and it makes it feel like I have someone yanking on the back of my seat. I think some of what is going on with it has to do with the P0300 code.

Im confident its not my rotor, distributor cap, fuel filter or plugs as I have replaced all of those with in the last year and half. I am going to check all the above soon, just a matter of getting my hands on the tools. About 2 years ago my fuel pump went out and I put a new one in, so I wouldnt doubt it might need a new one.

I want to check the fuel pressure but Im not sure what tool to look for, and I dont want to have to take it to a garage.

Any ideas on what I could do to figure out why it takes forever to start and/or how to stop the surging.

 

Please explain, multiple shots of what? Fuel?


If the parts you installed are not AC Delco, don't be too confident P0300, (random cylinder misfire) is almost always caused by a fault in the secondary ignition system: Spark plugs, spark plug wires, distributor cap, rotor and ignition coil. These engines are real fussy when it comes to these parts.


Again, if it's not an AC Delco pump, it's very possible the pump has a problem.


Most auto parts stores sell fuel pressure testers, usually run about $40. Low fuel pressure can also set the P0300, so it's a good idea to at least check the pressure and leakdown rate. This link will help you check the fuel delivery system for proper operation: https://blazerforum.com/forum/tech-a...agnosis-23038/

 

What I mean about giving it shots of fuel is that I have to apply the gas pedal several times, almost like I am revving the engine.

True words about the Ac Delco parts. Now I know my sparks for sure are AC Delco, and the fuel pump is Airtex.

If I am not mistaken, I think the rotor and cap are Duralast.

Wires I honestly have no clue about. I honestly have had them since I purchased the truck. I probably should replace them but in the past I hadn't had an issue with them and didn't see a need to.

How often should sparks be replaced? I changed them about a year and a half ago. I figured they would last a bit longer.

 

What I would suggest is replace the cap & rotor with AC Delco. Put a dab of silicone dielectric grease on each terminal, both inside and out, of the cap. Put the Duralast cap on the workbench and use it for an ash tray As for the wires, they are typically good for 100K miles. Autolite Professional Series wires have better specs than AC Delco wires at half the price. As for the Airtex fuel pump, check fuel pressure and leakdown. Key ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for 10 minutes after the pump shuts off. If it passes both tests, consider yourself lucky and leave it alone. Don't bother checking maximum pump output pressure; Airtex pumps fail that test when they're brand new, along with excessive noise, inacurate level senders, faulty pressure sensors, leaky check valves, wrong size O ring causing EVAP DTC's etc etc, best to let someone else buy them

Clear out all DTC's and perform a General Motors Driving Cycle to confirm your repair.

 

Update:

Thanks for the suggestions Cap'n. I will be trying those out soon, gotta make time between the car and the family. Also Today as I was heading to work my SES light came on, I was hoping it would stay on until I got home, lucky for me it did. It had three codes, P0300, P0452 and P0300(pending). Also beneath the codes there was a list of 9 issues that seem to go along with whats going on with my car.

As my code reader says:

6 Incomplete:
Catalyst
Evap
Sec Air
O2 Sensor
O2 Htr
EGR

3 Ready:
Misfire
Fuel
Comp

Any ideas on these? Thanks in advance guys!

 

The P0300 we already know, random cylinder misfire. The P0452 is a problem with the fuel tank pressure sensor, or its circuits. After the P0300 is repaired, clear the memory and perform a General Motors Driving Cycle to verify the repair. If the P0452 shows up again, diagnose and repair it, clear the memory and repeat the General Motors Driving Cycle. The pending P0300 means the PCM has detected random cylinder misfire again. The "6 incomplete" means those monitors have not run and completed their tests since the DTC's were last cleared. When you properly perform the General Motors Driving Cycle exactly as outlined, all of the monitors will run and complete their tests. The "3 ready" means those monitors have already run and completed their tests.

 

Can you rent a Fuel Pressure Tester at Oreillys or Autozone? I was looking online but couldnt find anything. Might buy one but would rather not since I probably wont use it too often.

 

Picture of someones homade, took pic to plumbing supplie house. Lucky, found a motor-head was more then happy to pck parts. Gauge was ten miss around ten and I had some stuff.

 

If you're planning on keeping your Blazer, a fuel pressure tester is a "must have" for your tool box. The picture in the above post is one that I made a few years ago. The beauty of that unit is that it will check fuel pressure, maximum pump output pressure and has the capability to isolate the fuel pump for locating excessive leakdown. It seems like all of the components cost about $25, including the gauge, male and female quick connect fittings, ball valve, fuel injection rated line, clamps, and brass fittings. The testers you buy at the parts stores are around $40 and they can not isolate the pump or check maximum output pressure. The tester connects inline at the fuel filter.

 

Would you only plug it in at one part of the line? Or do you move it around to different spots? And how do you check for all of those tests? Knowing me I would only get about one reading off of it and call it good.

Also where did you buy the parts for it? I have been itching for a DIY project aside from figuring out the misfire issue.